Biochemical tests

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Carbohydrate fermentation Broth What are we testing for?

testing to see if the organism can fermentGlucose, Lactose, Mannitol

How do you know if carbohydrate fermentation broth is positive or negative?

1 carb + pH indicator (Phenol red) if carb is fermented, acid end products will be released causing pH to drop. Red---> Yellow if acidic If there is gas in Durham tube, then non water soluble gases were given off, sign of some sort of reaction.

Why is a positive result in a carbohydrate fermentation Broth help/hurt organism?

if the carb can be fermented, then the organism can use the carb as an energy source.

O/F Glucose Test, What are we testing for?

testing to see does the organism do Aerobic respiration, Fermentation, or Both? (stab)

what is the benefit to the organism with a positive result to the nitrate broth test?

If it can use Nitrate as its terminal electron carrier then it can do anaerobic respiration. which is the second most energy efficient electron acceptor.

What are we looking for with the Starch test?

Testing for the ability to degrade starch using Amylase

What does a positive result look like?

Pour iodine over plateIodine + starch = black purple color If amylase is in organism, clearing will be seen around streak.

what is the benefit to the organism with a positive result to the starch test.

If the organism has amylase present then it is able to break down starch molecules (anything more than two glucose molecules, two glucose molecules= malose.) and bring them inside the cell for energy. amylase breaks down starch moecules down one by one.

What are we testing for with the Milk Agar?

Testing for caseinase? Caseinase is an enzyme that breaks down mile protein.

Media begins blue, dye binds to lipids in the agarAs bacteria grow, if they can use that fat, the break down and transport it into the cell leaving dye behind, Dark blue line (Dye build up) around growth if positive.

Benefit to organism if they have a positive result to spirit blue agar?

If lipase is present, it is the enzyme that will break down the fats to bring is into the cell.

what are we testing for in the Sulfide Indole Motility stab (SIM)

Sulfide= SO4 is in media as source of sulfer, Fe is also present. Motility= If cloudy everywhere, cells were motile. If entire tube is black then assumed motile because its not just black on stab line. Indole= tests for trytophan hydrolysis via trytophanase ****(KNOW STRUCTURE!!!!!!!!!!!)****

What does a positive test result look like in the SIM stab?

If sulfide is produced by the organism then S will react with FE in media to form FeS, a black ppt. If motile, then it will be cloudy everywhere or black everywhere. For Indole, add Kovac's reagent, Positive = kovac's layer will turn red (means indole is present)

What is the benefit to a positive result in the SIM stab?

The benefit to being a sulfide producer, is it helps determine between enterobacteriaThe benefit to being motile is it can move around to get the nutrients it needs, or leave a unfavorable environment. The benefit to Indole producer, is it helps determine between enterobacteria.

What are we lookinf for with the Urea broth test?

tests for urea hydorlysis via urease. ****( KNOW EQUATION)****

what does a positive result look like in the Urea broth test?

Positive result= Peach turns to Hot pink color.

What is the benefit to the organism that has a positive result for the Urea Broth test?

the ability to break down Urea via Urease is used to test the the differences between different bacteria.

What are we testing for with the Phenylalanine Slant?

Tests for Phenylalanine deaminase****( KNOW REACTION/DIAGRAM)****

What does a positive result look like in the Phenylalanine slant?

Add reagent FeCl3 to slantPositive result= growth turns green

What is the benefit to the organism that has a positive result to a phenylalanine slant

If the organism contains Phenylalanine deaminase then it can degrade Phenylalanine into phenylpyruvic acid and further to pyruvate and benzene (waste product)

what are we testing for in the Litmus Milk test?

testing for lactose fermentation Litmus= pH indicator

What does a positive reaction look like in the Litmus milk test

Acid end products will be released if lactose is fermented, causing pH to drop. Vigorous lactose fermentation could cause casin to precipitate. Purple(nuetral)-->Pink(slightly acidic)-->yellow(very acidic)

what is the benefit to the organism to have a positive result to the litmus milk test.

A positive result would indicate that the organism can degrade lactose, which is beneficial to the organism because it can use it as an energy source.

What are we Testing for in the Eosin methylene Blue (EMB) test?

Fermenting carbs, Lactose and sucrose. If either carb is fermented, acid end products are released, lowering pH.

Thiosulfate is in media as sulfer media also contains irons. If thiosulfate is used, sulfur is given off and sulfide reacts with iron in media which forms FeS, black ppt. Lactose fermented= pink coloniesSulfide produced = black colonies.

What is the benefit to the organism to have a positive result to the SS agar.

The benefit is it can ferment lactose and use it as an energy source.

What are we testing for in the triple sugar iron slant (TSI)

Fermentation of Lactose, Sucrose, and glucose. Lactose an sucrose at 1 % and glucose and 0.1%Stab and streak.Phenol red = pH indicator

What does a positive result look like in a TSI slant

Butt = yellow (acidic) = glucose fermented (should always happen) Slant = yellow (acidic) = Sucrose and lactose ( if yellow one or the other fermented, or both) Thiosulfate added as sulfur, media contains Fe. If thiosulfate is used sulfate is given off, it reacts with Fe, making FeS, black ppt. Sulferate is only active at acidic pH, meaning carb had to be fermented.

what is the benefit to the organism who has a positive result to the TSI

the benefit to the organism is if it can ferment the carbs, then it has another energy source.

What are we testing for in the Ornithine decarboxylase, Arginine Decarboxylase, Lysine decarboxylase test.

Tests to see if it can decarboxyate the carb. four tubes, first one is just a glucose decarb broth. then Orn, Lys, and Arg. pH indicator = bromresol Purple. (nuetral) Decarboxylase enzymes require a acidic pH ****(KNOW DIAGRAM)****

What does a positive result look like for the Ornithine decarb, Arginine decarb, and Lysine decarb test.

Decarb broth= should ALWAYS be yellow, if its not, then cant trust any of the results for that amino acid. Purple --> yellow (glucose fermented) then Yellow--> Purple (amino acid decarboxylated). Sealed with mineral oil, forces anerobic respiration.

What is the benefit to the organism that has a positive result for Orn decarb, Arg Decarb, and Lys decarb test.

the benefit is the organism can ferment glucose in an anerobic environment, and has Amino acids that help it survive.

bacteriophage

To eat bacteria. A bacterial virus. Virus attaches to bacteriaTakes over cell, turns it into a virus producing factorybacterial cell dies.